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From the above plot, it can be observed a large hysteresis which has to be investigated. The hysteresis decreases with the increase of the applied load.

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''First tests using the hard spring 350Nm/rad:''

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[[Image: KneeCalib2.jpg|300px]]

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Also in this plot the hysteresis is present, but it's constant with the increase of the applied load. The amount of the hysteresis is approximately comparable with the smallest one observed @ 10Nm with the soft spring.

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By removing the offset, it's possible to compare the two plots:

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[[Image: KneeCalib3.jpg|300px]]

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From the above plot, it can be noticed a non-linear response of the soft srping (plus the previously observed hysteresis).

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* The maximum deflection of the spring is +- 15 degrees (corresponding to about +-40Nm) The estimated spring constant is thus XXXX Nm/deg. Please check this data .

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* The accuracy of the defection sensor is 4096 counts for linear magnetic pole (2mm) This corresponds to a theoretic resolution of 0.488um = XXXX Nm. Please check this data .

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[[Image: FT1.jpg|300px]]

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[[Image: FT4.jpg|300px]]

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[[Image: FT2.jpg|300px]]

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[[Image: FT3.jpg|300px]]

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[[Image: FT1.jpg|200px]]

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* The tests performed by Alberto show a very good linearity of the spring can be observed (deflections sensor vs AVAGO encoder).

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[[Image: FT2.jpg|200px]]

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* The 'wavy' pattern probably corresponds to the change of magnetic pole on the strip. The amplitude of the waves is very small (about 10^-2 degs corresponding to XXXX Nm) Please check this data.

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[[Image: FT3.jpg|200px]]

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* A strange effect can be also observed. When the joint reaches its hardware limit, an offset is introduced in the deflection measurement (plot n2). Further investigation is required.

From the above plot, it can be observed a large hysteresis which has to be investigated. The hysteresis decreases with the increase of the applied load.

First tests using the hard spring 350Nm/rad:

Also in this plot the hysteresis is present, but it's constant with the increase of the applied load. The amount of the hysteresis is approximately comparable with the smallest one observed @ 10Nm with the soft spring.

By removing the offset, it's possible to compare the two plots:

From the above plot, it can be noticed a non-linear response of the soft srping (plus the previously observed hysteresis).

The maximum deflection of the spring is +- 15 degrees (corresponding to about +-40Nm) The estimated spring constant is thus XXXX Nm/deg. Please check this data .

The accuracy of the defection sensor is 4096 counts for linear magnetic pole (2mm) This corresponds to a theoretic resolution of 0.488um = XXXX Nm. Please check this data .

The tests performed by Alberto show a very good linearity of the spring can be observed (deflections sensor vs AVAGO encoder).

The 'wavy' pattern probably corresponds to the change of magnetic pole on the strip. The amplitude of the waves is very small (about 10^-2 degs corresponding to XXXX Nm) Please check this data.

A strange effect can be also observed. When the joint reaches its hardware limit, an offset is introduced in the deflection measurement (plot n2). Further investigation is required.